Both images were made with a combination of visible and infrared light to increase the contrast between water and earth. Water is dark blue or black, sediment-filled water or wet ground is light blue, clouds are pale turquoise and white, and the bare or sparsely vegetated Nubian Desert is tan-pink. Strips of vegetation along the banks of the rivers are bright green.
On September 6, the Atbara River had spread wide over its banks. The two branches of the river in the center of the image were so flooded that the two channels merged in a broad, shallow lake of muddy water. On the left side of the image, the Nile River is also wider than it was in July. The wider view provided in the large image from September 6 reveals that the Nile and its tributaries, the Blue and White Nile Rivers, were all swollen.
NASA images courtesy the rapidfire.sci.gsfc.nasa.gov MODIS Rapid Response Team at NASA GSFC, which provides rapidfire.sci.gsfc.nasa.gov/subsets/?NAfrica_2_07/2007249 daily images of Sudan.